1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* 3 * Copyright (C) 2003 Sistina Software 4 * Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved. 5 * 6 * Device-Mapper dirty region log. 7 * 8 * This file is released under the LGPL. 9 */ 10 11 #ifndef _LINUX_DM_DIRTY_LOG 12 #define _LINUX_DM_DIRTY_LOG 13 14 #ifdef __KERNEL__ 15 16 #include <linux/types.h> 17 #include <linux/device-mapper.h> 18 19 typedef sector_t region_t; 20 21 struct dm_dirty_log_type; 22 23 struct dm_dirty_log { 24 struct dm_dirty_log_type *type; 25 int (*flush_callback_fn)(struct dm_target *ti); 26 void *context; 27 }; 28 29 struct dm_dirty_log_type { 30 const char *name; 31 struct module *module; 32 33 /* For internal device-mapper use */ 34 struct list_head list; 35 36 int (*ctr)(struct dm_dirty_log *log, struct dm_target *ti, 37 unsigned int argc, char **argv); 38 void (*dtr)(struct dm_dirty_log *log); 39 40 /* 41 * There are times when we don't want the log to touch 42 * the disk. 43 */ 44 int (*presuspend)(struct dm_dirty_log *log); 45 int (*postsuspend)(struct dm_dirty_log *log); 46 int (*resume)(struct dm_dirty_log *log); 47 48 /* 49 * Retrieves the smallest size of region that the log can 50 * deal with. 51 */ 52 uint32_t (*get_region_size)(struct dm_dirty_log *log); 53 54 /* 55 * A predicate to say whether a region is clean or not. 56 * May block. 57 */ 58 int (*is_clean)(struct dm_dirty_log *log, region_t region); 59 60 /* 61 * Returns: 0, 1, -EWOULDBLOCK, < 0 62 * 63 * A predicate function to check the area given by 64 * [sector, sector + len) is in sync. 65 * 66 * If -EWOULDBLOCK is returned the state of the region is 67 * unknown, typically this will result in a read being 68 * passed to a daemon to deal with, since a daemon is 69 * allowed to block. 70 */ 71 int (*in_sync)(struct dm_dirty_log *log, region_t region, 72 int can_block); 73 74 /* 75 * Flush the current log state (eg, to disk). This 76 * function may block. 77 */ 78 int (*flush)(struct dm_dirty_log *log); 79 80 /* 81 * Mark an area as clean or dirty. These functions may 82 * block, though for performance reasons blocking should 83 * be extremely rare (eg, allocating another chunk of 84 * memory for some reason). 85 */ 86 void (*mark_region)(struct dm_dirty_log *log, region_t region); 87 void (*clear_region)(struct dm_dirty_log *log, region_t region); 88 89 /* 90 * Returns: <0 (error), 0 (no region), 1 (region) 91 * 92 * The mirrord will need perform recovery on regions of 93 * the mirror that are in the NOSYNC state. This 94 * function asks the log to tell the caller about the 95 * next region that this machine should recover. 96 * 97 * Do not confuse this function with 'in_sync()', one 98 * tells you if an area is synchronised, the other 99 * assigns recovery work. 100 */ 101 int (*get_resync_work)(struct dm_dirty_log *log, region_t *region); 102 103 /* 104 * This notifies the log that the resync status of a region 105 * has changed. It also clears the region from the recovering 106 * list (if present). 107 */ 108 void (*set_region_sync)(struct dm_dirty_log *log, 109 region_t region, int in_sync); 110 111 /* 112 * Returns the number of regions that are in sync. 113 */ 114 region_t (*get_sync_count)(struct dm_dirty_log *log); 115 116 /* 117 * Support function for mirror status requests. 118 */ 119 int (*status)(struct dm_dirty_log *log, status_type_t status_type, 120 char *result, unsigned int maxlen); 121 122 /* 123 * is_remote_recovering is necessary for cluster mirroring. It provides 124 * a way to detect recovery on another node, so we aren't writing 125 * concurrently. This function is likely to block (when a cluster log 126 * is used). 127 * 128 * Returns: 0, 1 129 */ 130 int (*is_remote_recovering)(struct dm_dirty_log *log, region_t region); 131 }; 132 133 int dm_dirty_log_type_register(struct dm_dirty_log_type *type); 134 int dm_dirty_log_type_unregister(struct dm_dirty_log_type *type); 135 136 /* 137 * Make sure you use these two functions, rather than calling 138 * type->constructor/destructor() directly. 139 */ 140 struct dm_dirty_log *dm_dirty_log_create(const char *type_name, 141 struct dm_target *ti, 142 int (*flush_callback_fn)(struct dm_target *ti), 143 unsigned int argc, char **argv); 144 void dm_dirty_log_destroy(struct dm_dirty_log *log); 145 146 #endif /* __KERNEL__ */ 147 #endif /* _LINUX_DM_DIRTY_LOG_H */ 148